LSAT 131 | Section 2 | Logical Reasoning: Q21

LR Question 21 Explanation

QUESTION TEXT: Essayist: When the first prehistoric migrations of humans

QUESTION TYPE: Weaken

CONCLUSION: The microorganisms that humans carried to North America probably caused the mass extinctions.

REASONING: It seems implausible that humans could have done it.

ANALYSIS: The argument doesn’t really give any evidence against hunting as a cause. They just say it’s “implausible”. The right answer shows that only those animals that were hunted went extinct: this weakens the disease theory.

___________

1. You might think “ah, this weakens the argument by showing that hunting was the cause!”
   But this answer actually strengthens the argument by showing disease can cause problems for animals. Even if hunting ultimately kills a diseased animal, the disease was still a cause.
   Note this also doesn’t say how much less able to avoid hunters the animals were. It could have been a small factor.
2. This might strengthen the argument by showing how microorganisms could kill animals but not humans.
3. CORRECT. This suggests that only hunted species died. This strengthens the idea that hunting was the cause, and weakens the alternate idea that microorganisms were the cause.
   Note that this isn’t contradicting the stimulus. The author didn’t say that hunting couldn’t be the cause. They just said it’s “implausible”, which means the author considers it unlikely.
4. This strengthens the argument by showing that humans could carry the extinction causing microorganisms without being sick and dying.
5. “Some” answers are very weak. This could refer to one species. That hardly affects the argument.